1. Field of the Invention
This invention pertains generally to abrading, and more particularly to wall surfacing sanders having a circular plate-like sandpaper holder manipulated at the end of an elongated handle.
2. Description of the Related Art
In the building construction and restoration trades, the finishing of walls will most preferably be completed with adequate care and precision so as to not reveal the various components used in the construction of the wall, nor their intersections, junctions and overlaps. More particularly, it is common practice to apply special tapes across abutted sheets of drywall or the like, and then apply thin layers of plaster, spackling compound or the like, depending upon the sheet material and application, over the tapes to smooth the transitions therebetween. Similarly, during repair and reconstruction, cracks or holes that require patching and repair will also be filled and smoothed to the surrounding wall. As a necessary part of the process, there will commonly exist a need to sand large areas of a wall. In some instances, once sanding has been completed, there will be revealed an additional need for plaster, spackling compound or the like, leading to a second round of applying the material and subsequent sanding.
These wall regions are very frequently located beyond comfortable reach. Consequently, sanding operations have heretofore involved either the use of ladders, with the requisite repositioning of the ladder for every few feet of wall to be sanded, the use of scaffolding which is both difficult to set up and which may interfere with access to a portion of the wall, or the use of special pole-mounted sanders that may be manipulated from the ground. Given the choices, at first blush to those less familiar with the operations, it might seem obvious to use the pole-mounted sanders. The pole permits a sander to travel along the ground and reach walls at great distances from the ground.
Consequently, a person may simply walk about, without climbing up and down ladders, and through “sweeping” motions, sand the wall. Since the person is already on the ground, replacement of sandpaper and the like is easy, as is access to other supplies, refreshments, and any other necessities required by the sander through the day.
Unfortunately, heretofore there have been several consequential drawbacks to pole-mounted sanders. One disadvantage has been a tendency for the sanding block to flip from the sanding surface over to the backing plate. As can be immediately understood, when the sanding block directly contacts the wall, there may be both undesirable material removal from the wall and also marking or material transfer from the block to the wall. Such an event may easily occur, owing to the length and natural flexibility of the pole, and difficulties with manipulating the sanding block smoothly over the surface. The surface may, of course, additionally be irregular or rough, further complicating the motion of the sanding block. When the block flips, the wall will require both patching and sanding. This can be particularly frustrating when an area was already essentially finished. Consequently, one false move may set the sander back several hours, and may require a return trip on a different day, after the wall material has had sufficient time to once again dry and harden. To make matters worse, a person must have a reasonable amount of strength and dexterity to manipulate the pole. While early in the work day this may be very routine, later in the day, just when the job is to be finished, the sander may be sufficiently exhausted to be more prone to the very mistakes in manipulation that will lead to the flipping of the sander and resultant wall damage.
A second disadvantage pertains to the geometry of most pole-mounted wall sanders. These have heretofore primarily used a rectangular sanding pad, which facilitates the sanding of an edge or straight line. However, it is very easy to run the rectangular pad along the same path too many times, thus forming a sanding groove. As those familiar with power sanding will recognize, orbital sanders were developed specifically to reduce the chance of forming sanding grooves.
A third disadvantage of the prior art pole sanders exists when a sander applies uneven pressure to the pole. This may be from twisting the pole, or the direction and motion required to reach a difficult-to-access place, or for other reason. Such uneven pressure may cause the undesirable flipping, but may alternatively lead to an uneven biting or digging into the relatively softer wall material. Once again, rather than blending the surfaces together, such uneven forces will tend to produce troughs or marks in the wall that only worsen the overall appearance.
While many of the foregoing disadvantages may be overcome using various apparatus and techniques, the opportunity to practically apply such apparatus and techniques just does not exist.
As but one example, a larger sanding pad will be less prone to flipping. However, the wall sander is at the end of a long pole, and the actual sanding block must therefore not be too heavy. From an understanding of physics, we can appreciate that while a one pound object directly held may seem to be relatively light, when it is at the end of a long pole, the forces necessary to move it about will be amplified by the relative distances between hands and to the end of the pole. This will make a weight at the end of a long pole seem to be much more. Consequently, while larger sanding blocks will be less inclined to flip, the additional weight may make them unmanageable for an entire work shift or day. Furthermore, the amount of force per square inch of sanding surface area that is necessary for the sanding operation to proceed effectively will be distributed over a larger area, thus again increasing the amount of total force, or muscle-power, that must be applied by the operator at the end of the pole. Once again, this extra effort will be required throughout the day, and will lead to undesirable fatigue for many persons.
Exemplary of the prior art is U.S. Pat. No. 6,524,175 to Beaudry et al, the contents which are incorporated herein by reference for the relevant teachings. Beaudry et al illustrates the standard prior art rectangular pad, which may be attached to either a hand grip or to a pole. The pole is disclosed as being coupled through either a universal joint or a ball and socket, though the ball and socket is not illustrated. Nevertheless, and as described herein above, the rectangular geometry of the sanding block is actually quite dangerous to be used with a ball and socket, since the sanding forces will readily concentrate at the corners of the pad, and, with a ball and socket, may not be countered by manual forces upon the pole. Said another way, if a corner of the sanding block starts to bite into the wall, which will certainly damage the wall and which could lead to the pad flipping, an operator will not be able to simply twist his grip with the ball and socket, since a ball and socket joint will not transfer such forces to the pad. Consequently, the universal joint illustrated by Beaudry et al and similarly in the other prior art, which permits controlled twisting of the pad, has been much preferred over a ball and socket.
U.S. Pat. No. 5,144,774 by Conboy, the teachings which are incorporated herein by reference, illustrates a ball and socket between head and handle, but with rotation preventing grooves in the ball and keys in the socket. U.S. Pat. No. 4,663,796 by Helling et al, the teachings which are also incorporated herein by reference, illustrates a quick-release handle that is attached to the male threaded pole by a female thread. Additional patents, the teachings of each which are further incorporated herein by reference, include U.S. Pat. Nos. 1,501,192 by Severns; 2,434,581 by Ottoson; 2,663,979 by Sierchio; 2,711,059 by Ames; 2,753,669 by Larson; 2,817,931 by Houser; 3,123,946 by Hoveland; 3,279,130 by Nelson; 3,483,662 by Ames; 4,885,876 by Henke; 5,036,627 by Walters; 5,301,472 by Lyng; 5,392,569 by Stickle; 5,709,597 by Sarantitis; 5,954,571 by Case; 6,053,805 by Sanchez; and 6,325,708 by Miles. Nevertheless, these documents fail, either singly or in combination, to overcome the limitations outlined herein above. What is desired then is a pole-mounted sander which overcomes the many disadvantages of prior art pole sanders.